Blue light usually comes from the sun but also from digital screens and LED lights. Some experts believe artificial sources may be causing eye damage in humans, but animal studies are inconclusive.

The sun is the greatest source of blue light. Natural blue light helps regulate your circadian rhythm, or wake-and-sleep cycle. Sunlight is also instrumental in children's eye development.

Together, they make the white light you see when the sun -- the main source of blue light -- is shining. Fluorescent and LED (light-emitting diode) light bulbs also give off blue light.

Think blue light is hurting your sleep cycle? A new study suggests it can actually improve the overall sleep quality of older adults — but only if they time it right.

Ever wondered why the sky is blue? It's not just a reflection of the ocean! Sunlight, seemingly white, is a mix of colors. As ...